Currently there are 16 native Telephoto Zoom lenses for Panasonic GX8 and all of these lenses are autofocus (AF) type.
GX8 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on GX8.
Since Panasonic GX8 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 5 Telephoto Zoom lenses with Weather Sealings.